a(n) contains n digits (either '4' or '7') and is divisible by 2^n.
A053332
a(n) contains n digits (either '4' or '7') and is divisible by 2^n.
Terms
- a(0) =4a(1) =44a(2) =744a(3) =7744a(4) =47744a(5) =447744a(6) =4447744a(7) =44447744a(8) =444447744a(9) =4444447744a(10) =74444447744a(11) =474444447744
External references
- oeis: A053332